Magnetic recording



April 20, 1954 B. ROBERTS 2,676,022

MAGNETIC RECORDING Filed March 17, 1949 4 Sheets-Sheet 1 INVENTOR. 5Puc @551??- ATTO/PNE K s April 20, 1954 B. ROBERTS MAGNETIC RECORDING 4 Sheets-Sheet 2 Filed March 17 1949 r ORA/5K9 April 1954 B. ROBERTS MAGNETIC RECORDING 4 Sheets-Sheet 3 Filed March 17, 1949 April 20, 1954 B. ROBERTS MAGNETIC RECORDING 4 Sheets-Sheet 4 Filed March 17, 1949 If III I I ll. I. \M W Q INVENTOR. BRUCE A 055? T5 BY 49% ,4 r Top/v1; KS

Patented Apr. 20, 1954 MAGNETIC REGORDIN G BrucerllobertsnLos Angeles, Calif., assignor to I Ernest. G. VanLeeuwen andoAlfred W. .Neely,

.both of'Los Angeles", Calif.

Application March 17, 1949, SeriarNo: 81,983 I 54Claims. (Cl. 274-.4)

erated with azminimum .amnuntizof instruction. v

\ It is therefore an objecttofitheapresentz::invention to provide -.-an improved. recording and. reproducing; device which. meet: ,these desiderata. .;Another :object of the. presentflinvention is to provide "an improved recording and reproducing device whichis of small physical dimension but yet allows the recording: and reproduction of intelligence .forarelatively. long periodrof time without "the necessity of changing .the-.;sensitized medium.

Another object: of the-present inventionis to provide an improvedreproducing and recording device-of atype in which a magnetichtape is mounted to vrun in alternately opposite. "directions past an: electromagnetic devicecontrolledby :electric impulsesforzmaking a plurality of. magnetic record tracks on the tape, and wherein means are provided vfor automatically rreversing.the movement of the. tape at the. end: of a record track and for shiftingthe electromagnetic device laterally of the tape when the tape;is.;.r.eversed in direction, a characterizingieature of thepresent inventionrbeingz that theitapesis alwayszdriven by a 'nonreversible constant; e speed motor driven shaft in a manner asto minimizethetime interval necessary: to move therecording device from one track-tozthe inextr ad jacent trackhat th end of arecord track.

Still another objector .the present invention is to providesanl. improvedrecording: and, reproducing device ofthe :type described inthe-nextgpmceding paragraph'acharacterized in that a novel drive is provided which is automatically-audaclectively operated to. alternately drive eitherione of two tape drumsby asingle;nonreversibleaconstant speed motor'drivenshaft.

Yet another object of the present vinvention is to provide an improved recording and reproducing apparatus of the typeJdescribed above, characterized: in that a.novel-means is provided for moving theelectromagnetic'device; to different channels.

The features of thepresent invention-which are believed to beznovel are:set'iorth withsparticularity in therappended-claims 'Ihis-rinvem tion itself,r,bothv-v as toits organization andtmanner. of operationptogether with. further objects and advantages zthereofpmay be best understood by reference to "the following description taken in connection with. the -accompanying drawings. inwhich:

-*.Figure' his a perspective view of a recording and reproducing .apparatushembodying features of the present invention,

Figure 2, is a: perspective view of the back of the apparatus-shown in Figure 1 but with the metallic shield removed from theelectromagnetic transducer.

Jiiguret isacomhined perspectiveand sectional view ttakensubstantially on the line :l3 of Figure 1.

Figure 4 is a: perspective view similar to, the perspective-view shownzin; Figure 2, but with the magnetic tape and thestapeedrums removed.

Figure 5- is a perspective:-view-showing details of the. pver centeredishuttle bar and the-lost-motion connections between such shuttlewbar and they-axle supports forthezpucks (not shownvin Figure 5) which are z-usedto; drive alternately the corresponding, tapesdmm.

;.Figure 6 isfla view taken substantially on the line 6.-16-. of Figure '7.

Figure 7 is a view takensubstantially on the line 'l---'|--ofv Figure 2'.

Figure 8 is a perspective view showing details of the electromagnetic;transducer positioningap-i paratus'embodiedin.thedeviceshown inlFigure 1,

Figure 9 is a diagrammatic representation for illustrating thedispositionofv;the parts of the electromagnetic vtransducer in; relationship" to the magnetic tape passing adjacent thereto,

Figurev 10 is a diagrammatic representation showing tthe manner in' which the-magnetic tape isreelecl. on the-two tape; drums.

- JEigu-re l1 is.asectional view. taken substantially on thetlinepl l'---l l of Figure 5 .Figure moist-another sectional view illustrating details of;the, -apparatus shown in Figure 1.

Therecorder and 'reproducer is characterized by its relatively small dimensions accomplished to a large extent; by the use'of; arelatively wide magnetic tape: lllpupon-whichseries of recordings may :be. made: generallyalong' the lines 1 I, I2,- 13, 14', etcnrsuch recordings beingrmade and reproduced-whenand as the. tape 10 travels a1- ternately in opposite directions, as indicated by the arrows HA,: [2A, t3A-and A. These lines I I, l2, l3 and" Itmaytbe termed record tracks.

An important feature vof the .present. invention isthe magnetic mech-anism whereby'the re- I cording and reproducing head or electromagnetic transduceron device :20 is automatically. dropped down to the next channel, i and 1 simultaneouslythe directions: of rotation of 'thertape. drums. 2 I and ;2-2rare ,reversedsat"the end of a channel or I record track or, in g other words,v when the tape I0 is almosttcompletely reeled off one of the drums 2], 2:2, as the case may :be.

The r tape I ll is ;threaded. andv .maintained'nn the drums '2 t, 22 :asindicated. in.,Eigu1es 1 "and 10, 1 and is adapted to travel between .thehmagfnetically cooperating parts Z'OAL' znp'rr'igure'm' of the electromagnetic transducer 20. The electromagnetic transducer 20 may be of the type which may be used both for recording and reproducing, wherein the tape l travels past the air gap 200 in the horseshoe type of magnetic field structure 20D, having mounted thereon the current coils 20E for producing a magnetic flux between the air gap 200 and the plate 2013. Plate 203 is of magnetic material.

Of course, it is understood that the electromagnetic transducer 20 may take other forms and shapes, and the particular one shown in Figure 9 is merely exemplary of those which 4 bottom of the case 33, with its shaft 32 projecting above the mounting, plate, as shown in Figure 4. This .motor driven shaft "32 1 is always oriented in the same direction, but the rubber rimmed driving wheels 35, 35, as the case may be, are automatically brought into engagement with :the motor driven shaft 32, depending upon the position of the slide or shuttle bar 21. As

- indicated in Figures 6 and '1, the driving wheel may be used, it being noted that the electro-' magnetic transducer per se forms no part of the present invention, and in the actual transducer shown in Figure 8 the paper is inserted between the plates 63 and 64. The upper end of plate 64 is curved to form a lip whereby the tape ||J may conveniently be placed between the two plates 63, 64.

This electromagnetic transducer is movable in a vertical plane in guide grooves in the spaced standards 6|, 62 in the manner described hereinafter.

Referring to Figure 3, each one of the drums 2|, 22 carries internally thereof on bracket 22A a pivoted gravity actuated arm 25 which is pivoted at 223 with one of its ends 25A normally in engagement with the innermost tape turn on the corresponding drum, to thereby normally maintain the other end 253 in raised position. After substantially all of the tape is reeled from the drum 22, for example, the armor dog 25B automatically drops to thereby allow it to engage and move the manually operable extension or lever 26 which is afiixed to the slide or shuttle bar 21, which is movable longitudinally, as indicated by the arrows 2B in Figure 5. It is noted that the lever extension 25B in Figure 3 contacts the operating lever 25 whereas the other lever '25, 'pivotally mounted in the other drum 2|, is adapted to engage and to move the extension 213 on the shuttle bar 21 to produce the same results.

Thus, as the drum 22 continues to rotate, near the end of a record track, the dog 25B mounted in either drum2| or drum 22, as the case may be, causes the slide or shuttle bar 21 to move longitudinally, such motion of the bar 21 being guided by the combined supporting and guiding structures 29, 30 which are affixed to the mounting plate 9 in the manner indicated in Figure 11. The shuttle bar 21 is normally maintained in either one or its two extreme positions by the over-center mechanism 30, comprising the tension spring 3| and the levei 32A pivoted about the axis of the stationary pivot pin 33 which is mounted on the mounting plate 9, it being noted that one end of the spring 3| is fastened to the post 3|A mounted on the plate 9, while the, other end of the spring 3| is affixed to one of the free ends of the lever 32A. The other end of the lever 32A carries an abutment 34 which is snugly received in an aperture in the bar 21 providedby down-turned ears in the bar '21, as shown in Figure 5. Thus, the lever 32A is pivoted at a point intermediate its ends and serves to maintain, with the aid of the over-center spring 3 I, the shuttle bar 21 in either one of its two extreme positions.

One of the tape drums 2|, 22 is always in driving engagement with the constant speed nonreversible motor driven shaft 32 of a conventional phonograph type of motor mounted the or puck 35 is arranged to rotate the drum 22, and the other smaller driving wheel or puck 36 is arranged to move into engagement with the drive shaft 32 to drive the other drum 3|. It is noted that at any one time, only one of the drums 2|, 22 is driven and in such direction to reel and'unreel the paper tape from one drum 2| to the other drum 22, and vice versa, and that when one of the drums 2|, 22 is being driven by the shaft 32, the other is free to rotate in their mountings described presently.

The drums 2|, 22 are rotatably supported on suitable anti-friction bearings-which are mounted on the corresponding stationary posts 2|C, 220 .(Figure 4). The weight of the drums 2|, 22 is carried on the corresponding anti-friction bearing members 2|D, 22D. The drums 2|, 22 may be moved vertically with .respect to the stationary posts 2|C, 220, as for example, when such drums are assembled on or removed from their positions" with respect to the posts 2|C, 22C. 'The two drums 2|, 22 together with the tape reeled on each may thus be removed from the device as a unit by'simply pulling upwardly on the two drums 2 22 simultaneously, in which case the tape H) is free to slide between the two plates 53, 64 (Figure 8) of the transducer 23.

It is noted that the drums 2|, 22 are somewhat different structurally in that, as shown in Figures 6 and'7, the drum 2| .is provided with acircular flange adapted to be contacted internally by the driving puck 36, while the other drum 22 has a similar flange which is adapted to be con ta'cted externally by the other driving puck 35. In order to assure a good driving connection, on the one hand between puck 36 and drum-2|, and on the other hand between puck 35 and drum 22, the shafts forsuch rotatable driving pucks 35', 36 are floatingly .supported with respect to the mounting plate 9, so 'as to allow such driving pucks 35,36 to move in their respective planes of rotation. For this purpose, the shaft 35A for driving puck 35 is mounted on the triangular floating plate 40, and the shaft 36A, about which the other driving puck 36 rotates, is mounted on the arm 45 which is longitudinally slidable in the pivoted block 49, which in turn is pivoted about the axis of the pivot pin 5|! aifixed to the mounting plate 9.

The triangular plate 40 may pivot with respect to the stationary pivot pin 41 mounted on the mounting plate 9, or may slide with respect to the stationary pin 41 because of the enlarged slotted portionlflA therein through which the pin 41 passes. Such floating movement of the plate 40 is limited to a certain degree by the stationary stop member 49A, which is afiixed to the mounting plate 9 but spaced a slight distance from the triangular plate 49.

Thus, the shafts 35A, 36A for the corresponding driving wheels or pucks 135, 36 respectively are fioatingly mounted, i. e. the shafts 35A, 33A may move in'either one of its radial directions in a horizontal plane. These shafts 35A, 36A are moved upon movementof slide plate 21 from one of its over-center positions to the 'other oneof its pverrcenter .zplositions, it being: noted; however, that the plate 40 and. arm 52,;attached-to thezpivotablei block- 4.9, are eachxcoupledtotthe shuttlebar :21 through a'lost motion connection represented generally .by the reference numerals 55, :56. These lost motion connectionsr55, 56 are, as. shown in Figure 5, obtained bylproviding suitably enlarged and: spaced'openingsiinhthe shuttles-bar Elinto which an extension 400 and 52A respectively may extend. The openings-21E "and 21:5 in .the .plate 21, intowhich the members 490 and, 52A respectively extend, are-of such dimensions. that, in one of the over-center positions of the-bar 21'the shaft 36A is movecl to interposition its driving puck36 betweenrthe motor driven shafti32 .and the corresponding drum memberxZ I, m thereby establish a driving, connection: therebetween, while .the:member 400 is free to :move in the-slot 21E to, in turn, allow therassociated'drivin'g puck. 35 to move out of engagementwith. the correspondingdrum 22. Similarly, in the other over-center position of the bar 21, the extension 400' issengaged between: walls defining the slotted portion 21E to cause the associated driving puck. 35 to move in a position between the motor drivenshaft 32 and the corresponding drum 22, to establish a driving "connection therebetween, while-the. otherdriving puck 36 is free to move out 'of driving:.engagement with itsiassociated tape drum 22.

' :Thus',rin one of its over-center positions the bar 21 is eflective to establish a driving connectionwith the'tape drums 2|, 22, and in the other over-center position of bar 21 a driving connection is establishedwith the other one of such tape drums 2|,i22.

It is noted that the purpose of floating the supports for the shafts 35A, 36A is to allow the drive wheels 35, 36, as thecase may be, to move into a more binding or:locking.. engagement with theassociated drum to provide a more positive driving connection to thereby prevent slippage. i :The' electromagnetic transducer 26is vertically slidable' inxtheiguide: slots in the two vertical stationary posts 6!, 62 (Figure 8) with the magnetic tape disposed between the members 63,- 54. The transducer 20 is normally maintained stationary while the tape isbeing reeled from one drumonto the other drum; but when subtantiallyall of the tape is removed .from one of the drums the shuttle bar 2'! is moved longitudinally to automatically allow the transducer 20 to move tQJthe'neXt lower channelor track on:the tape l0. For this purpose, the transducer 20 is supported on one of a plurality of vertically disposed staggered steps 65 on the pivotally mounted post 66. The post-66 is mounted for pivotal movement about the axis of the stationary pin 61. This pivoted post 66 carries an extension 66A received in a notch 2TB in the slide plate 2'! so as to move with the slide plate '21.

Thus, when the post 66 ispivoted, the transducer' 2fl-and attache-d support 66 are allowed to fall by; the action of gravity forces thereon on to theinext lower adjacent staggered step 65, in accordance with the movement ofv the shuttle bar 21.. l Thus, as the shuttle bar This progressively oscillated, either by manually operating the lever 26, or automatically at the'end of a record trackrbythe gravity actuateddogs or levers 25 (Figure 3) associatedwith each one of the drums 2|; 22,.the transducer: 20 is progressively lowered. This featurev allows one to .move the transducer 20 zidownwardly by manually operating the handle'ior lever-12.61 withoutpthe:neeessity; ot xrunning the gtape to the: endzof a; record track.

oAlso the transducer: 2flzsmayibec moved upwardly manually-without the;necessity of.-,running the tape zzby? first rotating the .;handle-l.=0 associatedl therewith clockwise: in-Figure, 8, "to therebysrotate thesupport 68 vin1the direction indicated: by the arrow ll.;::and thereafternthe transducerl 2'0nnay' be :movedtup or 1 down to .a position wherein-tonetof the indicia. 12 iisadjacentia. reference smarlcprovided; for example; by thexupper edge-.otthe zmounting plate 9.. For this .purpose :.it. is :noted ithat the' handle 10 comprises the endxofiaibent shaft which 18310- tatablyzsupported...in arhalf round rod-lirof transparent Lucitetwhich: isvaflixed. to the plate l4.,.=anc1. which has-ltheaindicia .12.vv .This handle T0 is :attached: to .the support 68 .which has an ear 68A extendingliupwardly therefrom to serve as a stop member for engagement -with the Lucite' 15, it being noted that such stop member 68A is normally biased in engagement with the Lucite IS-by the torque spring '11.

' Preferably, the machine is'loaded with tape mc intedona cylindrical spool 90, as shown in Figure '10, such spool having anaperturedportion A through which the finger 25A "is adapted to engage the innermost-turn of the tape on the reel 90.- --Suchreel" 96 is closed'at its upper enchas shownin figure 1, and "is adapted to slip overthe z-dru-m' 22." order-to properly orient such reel' 9 0 with respect to the drum 22, and also to prevent such reel from slipping with respect to the drum 22, there is provided an indexing andholding pin 91 which is mountedon the base of the drum 22,- as indicatedin Figure 3, with :such pin 91 adapted to project through an indexing aperture 90B in the upper closed end of- -thereel 90. Thuswhen the reel 90, with the tape mounted thereon, is properly loaded onto the machine, with. the pin 9! projecting through the aperture 96B, the slot 90A is properly oriented with=the finger" 25A to allow such finger 25A -toproject through the slot and. engage the innermost tape turn.

- Theinnermost' tape turnon the-reel 90- may bee-secured thereto by using "different expedients and; .as shown-in the drawings the end ofsuch innermost tapel turn is gluedto the ree'l flil as indicated at 92 in Figure #10. '.Preferably;-such innermost Jtapeend is affixedtethered-90' as close as is practically'possible to the slot 90A through which the finger 25A is adapted'to project. Afterthe tape spool' is thus 'loadedon-the drum 22,: 'the-outer-end of-the tape is partially wound around the other drum' 2l'and inserted through i the :tape holding slot 2i A- therein, with the paper bent back upon itself as shown 'in Figure 10. ':'.The tape slot. 2IA 'positionedin a definite. relationship with-respecttosthe .tape engaging finger .25 associated with the l Idrum 2| to. obtain cinching actionbetween the tape and thev drum- 2|, to. therebywprevent undue stressingof theitape whereit passes through thelaperture vZIA to avoid. tearing of the tape at that point.

"Referring to'Fi gurelO, the tape .lil iscbeing reeled from the drum 2! onto the spool 96', and the drum 2| travels in the direction indicated by the--'arrow' 95. This corresponds to theiend of tape -travelfrom--drum2-'l to the spool" 90, and themechan-ism'is' att-he point of tripping so as to automaticallycause the tape Ill to reverse its dire'ction of travel with subsequent reeling of the tape from the spool 90 onto the drum 2|. It is noted that at such point of tripping the paper I produces a cinching action with the circular drum 2| to prevent undue stressing of the tape at the aperture 21A. Preferably, the annular distance between the slot 21A and the point 96, under these conditions, at which the tape first engages the drum 2|, is greater than ninety degrees measured in the direction indicated by the arrow 91.

While the particular embodiments of themes.- ent invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. Apparatus of the character described, comprising a pair of record drum members arranged to alternatively transfer a record from one drum member to the other, a motor driven shaft, a single shuttle bar movable substantially rectilinearly, a corresponding driving puck member for each of said drum member, each puck member being alternately moveable into engagement withsaid motor driven shaft to thereby drive its corresponding drum member, said puck meznbers being floatingly mounted and actuated by said shuttle bar for free movement in their planes of rotation into direct engagement with their corresponding drum member, and means operated automatically when substantially all of said record is transferred from one drum member to the other drum member to move said shuttle bar, said means being effective to move said shuttle bar in opposite directions to corresponding extreme positions wherein a corresponding one of said puck members is pressed into engagement with a respective one of said drum members.

2. In recording apparatus of the type in which a magnetic tape is mounted to run in alternately opposite directions adjacent an electromagnetic device energizable by electric current for making a plurality of magnetic record tracks on the tape, and wherein there is present means for automatically reversing the, movement of said tape at the end of a record track and for shifting the device laterally of the tape when the latter is reversed,,the improvement residing in providing a nonreversible constant speed motor driven shaft, a pair of drum members carrying said tape arranged to be alternately driven to thereby move said tape in said alternately opposite directions, a member movable to different positions, a pair of puck members floatingly supported on said member, each of said puck members being arranged for driving a corresponding drum member, each puck member being alternately moveable into engagement with said motor driven shaft to thereby drive a corresponding drum member, each 02 said puck members having a corresponding shaft support, a lost motion connection between said member and each of said shaft supports, a structure movable in accordance with said member having a plurality of vertically disposed staggered steps for supporting said electromagnetic device, said structure being movable in accordance with movement of said member to allow said electromagnetic device to move, under the influ- 8 ence of gravity forces, onto the next adjacent lower staggered step.

3. In recording apparatus of the type in which a magnetic tape is mounted to run in alternately opposite directions past an electromagnetic device energizable by electric current for making a plurality of magnetic record tracks on said tape, and wherein means are present for automatically reversing the movement of said tape at the end of a record track and for shifting said device laterally of the tape when the latter is reversed, the improvement residing in providing a pair of drums for said tape, a support for said drums, a member automatically movable on said support when said tape reaches the end of a record track, one of said drums having an internal driving flange and the other one of said drums having an external driving flange, a constant speed nonreversible motor driven shaft, a pair of driving pucks each arranged to drive a corresponding one of said drums, said driving pucks each having an axle support floatingly mounted on said support for movement in a plane substantially parallel to their corresponding planes of rotation, a lost motion connection between each axle support and said member, over-center positioning means associated with said member to maintain said mem-' ber in either one of two positions wherein a corresponding one of said axle supports is moved to interposition its corresponding driving puck between said constant speed shaft and the corresponding flange on the corresponding drum.

4. The invention defined in claim 3 characterized by the fact that each drum carries a lever adapted to engage said member but normally maintained out of engagement therewith by the tape on the drum.

5. The invention defined in claim 3 character ized by the fact that said electromagnetic device is supported on one of a plurality of vertically disposed staggered step members, said plurality of step members being moved with said member to allow said electromagnetic device to drop down onto the next adjacent staggered step.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,108,501 Kirchhoff Aug. 25, 1914 1,343,628 Jenkins June 15, 1920 1,366,182 Hokanson Jan. 18, 1921 1,560,721 OReilly Nov. 10, 1925 1,789,607 Steurer Jan. 20, 1931 1,814,706 Karrer July 14,1931 1,971,028 Bothe Aug. 21, 1934 2,032,190 Thomas Feb. 25, 1936 2,275,961 Heller Mar. 10, 1942 2,408,320 Kuhlik Sept. 24, 1946 2,430,538 Somers Nov. 11, 1947 2,467,507 Stone Apr. 19, 1949 2,468,198 Heller Apr. 26, 1949 2,486,473 Hart Nov. 1, 1949 2,487,170 Nygaard Nov. 8, 1949 2,488,482 Swarthout Nov. 15, 1949 2,535,478 Arndt Dec. 26, 1950 2,610,808- Davis Sept. 16, 1952 2,614,760 Danisch Oct. 21, 1952 FOREIGN PATENTS Number Country Date 390,878 Germany Feb. 25, 1924 392,641 Great Britain May 25, 1933 471,713 Great Britain Sept. 9, 1937 852,767 France Nov. 9, 1939 

